Vacuum furnace and common uses

A vacuum furnace is a furnace in which the products in the furnace are surrounded by vacuum during processing.The absence of air or other gases prevents oxidation,product heat loss through convection,and eliminates sources of contamination.This allows the furnace to heat materials (usually metals and ceramics) to temperatures of up to 3,000 °C (5,432 °F) and select the material.The maximum furnace temperature and vacuum depend on the melting point and vapor pressure of the material being heated.Vacuum furnace is used for annealing, brazing,sintering,heat treatment and other processes,with high consistency and low pollution.

Characteristics of a vacuum furnace are: 

Uniform temperature over range. 800–3,000 °C (1,500–5,400 °F).

Commercial vacuum pump systems can achieve vacuum levels as low as 1×10−11 Torr (1.3×10−11 mbar; 1.3×10−14 atm).

The temperature can be controlled within the heated zone, which is usually surrounded by insulation or insulation.

Low contamination of product with carbon, oxygen and other gases.

Vacuum pumping systems remove cryogenic by-products from process materials during heating, resulting in a higher purity end product.

Rapid cooling (quenching) of the product can be used to shorten process cycle times.The process can be computer controlled to ensure repeatability.Heating metals to high temperatures in the atmosphere often results in rapid oxidation,which is undesirable.A vacuum furnace removes oxygen and prevents this from happening.Inert gases, such as argon,are often used to rapidly cool the treated metal back to non-metallurgical levels (below 400 °F [200 °C]) after the desired process is complete in the furnace.This inert gas can be pressurized to twice the atmospheric pressure or more,then circulated through the hot zone area to absorb heat,which is then removed by a heat exchanger.This process continues until the desired temperature is reached.

Common uses

Vacuum furnaces are widely used in production industry and research laboratories.Vacuum furnaces are commonly used for heat treatment of steel alloys at temperatures below 1200 °C.Many general heat treating applications involve the quenching and tempering of steel parts to make them strong and durable in service.Hardening involves heating the steel to a predetermined temperature followed by rapid cooling in water, oil or a suitable medium.Another application of vacuum furnaces is vacuum carburizing, also known as low pressure carburizing or LPC.In this process, a gas, such as acetylene, is introduced as a partial pressure into a hot zone, typically at a temperature between 1,600 and 1,950 °F (870 and 1,070 °C).The gas is broken down into its constituent elements (in this case carbon and hydrogen).The carbon then diffuses to the surface area of the part.This function is usually repeated, varying the duration of the gas input and the diffusion time.Once the workload has been properly "boxed", the metal is quenched using oil or high pressure gas (HPGQ). For HPGQ,nitrogen or helium for rapid quenching is usually used.This process is also known as surface hardening.Another low-temperature application of vacuum furnaces is debinding,a process that removes binders.Heating under vacuum in a sealed chamber melts or evaporates the binder in the aggregate.The adhesive is expelled by the pumping system and collected or removed downstream.The higher melting material remains in a purified state and can be further processed.Vacuum furnaces capable of withstanding temperatures above 1200 °C are used in various industries such as electronics, medical, crystal growth, energy and synthetic gemstones.Processing of metallic and non-metallic high-temperature materials in a vacuum environment, allowing annealing, brazing, refining, sintering and other processes to proceed in a controlled manner.

Vacuum furnace parts

Vacuum furnace parts are widely used in various industries.Vacuum furnace maintenance is a method of protecting hot steel and metal components from the harmful effects of the air environment.Vacuum furnace components are usually electrically heated furnaces that maintain vacuum throughout operation.Resistive elements made of graphite, ceramic or metal heat most vacuum furnace components.